1. Field of the Invention
The present invention relates to a liquid crystal display device, a manufacturing method of a liquid crystal display device, a display device and an information input apparatus. Particularly, the invention relates to a liquid crystal display device, a manufacturing method of a liquid crystal display device, a display device and an information input apparatus, in which a touch sensor switch is provided on a pair of substrates opposite to each other.
2. Description of the Related Art
A display device, such as a liquid crystal display device or an organic EL display device, has merits such as low thickness, lightweight and low power consumption. Thus, the display device is often used in a mobile electronic equipment, such as a cellular phone or a digital camera.
In the display device as stated above, the liquid crystal display device includes, as a display panel, a liquid crystal panel in which a liquid crystal layer is sealed between a pair of substrates. For example, the liquid crystal panel is of a transmission type, modulates an illumination light emitted by an illumination device, such as a backlight, provided on the back of the liquid crystal panel and allows it to pass through. Then, an image is displayed on the front of the liquid crystal panel by the modulated illumination light.
For example, the liquid crystal panel is of an active matrix type, and includes a TFT array substrate on which plural thin film transistors (TFTs) functioning as pixel switching elements are formed. In the liquid crystal panel, an opposite substrate is disposed so as to be opposite to the TFT array substrate, and the liquid crystal layer is provided in a space between the TFT array substrate and the opposite substrate. In the active matrix type liquid crystal panel, a voltage is applied to the liquid crystal layer by inputting an image signal to a pixel electrode through the pixel switching element, and the transmittance for the light passing through the pixel is controlled, so that the image is displayed.
In the display device as stated above, in order to enable a user to input operation data by using an image, such as an icon, displayed on the screen of the display panel, there is a case where a touch panel is provided as an information input device on the display panel.
However, when the touch panel is externally disposed on the display panel, the whole thickness becomes large, and there is a case where the merit of low thickness is lost. Besides, since there is a case where the transmitted light is reduced in the display area by the touch panel or the light interferes, the quality of the display image can deteriorate. Further, disadvantages such as reduction in manufacture efficiency and increase in manufacture cost can occur.
Thus, a display device is proposed in which the display panel has a built-in touch panel function.
For example, a liquid crystal display device is proposed in which the liquid crystal panel has a built-in resistive film type touch sensor.
Here, the touch sensor includes a touch sensor switch in which a touch electrode is provided on each of a pair of substrates constituting the liquid crystal panel, and when the liquid crystal panel is pressed and is deformed, the pair of touch electrodes are electrically connected to each other. In the liquid crystal panel, the touch electrode is provided on a convex part protruding convexly, so that the touch electrodes formed on both the substrates are electrically connected to each other by a small external pressure (see, for example, JP-A-2001-75074 (patent document 1), JP-A-2007-52368 (patent document 2) and JP-A-2007-95044 (patent document 3)).
In the liquid crystal panel, a liquid crystal orientation film is provided in order to orient liquid crystal molecules in the liquid crystal payer. With respect to the liquid crystal orientation film, it is proposed that a surface portion of the touch electrode is removed, and the surface portion is exposed.